Hi chamois,
I used to fish it when I lived in the Southend area many years ago, but maybe it hasn't changed much since (apart from the flooding of the farmland east of Wallasea).
I used to fish it for bass on the south side, which is the deepest, and it's also the side that is rocky - which is more to their liking. The flood is best - on the ebb the water movement is much too strong to hold bottom, and the fish probably don't want to feed under those conditions anyway. Spring Tides can be a problem with debris and filth in the water - go when thye tides are lighter. Daytime fishing gives best results because the water is silty and it proivides cover for the bass; night brings forth too many eels. As you are camping there is no excuse - fish daybreak, before all the boats start zig-zagging about, frightening off the fish. Use crab, or failing that, ragworm, on a short snood, say 12 to 18 inches, and a breakout lead, and cast 45 degrees uptide. Fish from 2 hrs beyond low water to High Tide. Lob the legered bait into a gap in the floating weed, or to just beyond the floating weed. Don't cast out further - it's just barren. Use a shortish handled rod (I used to use a boat caster, which has plenty of backbone if you get a biggie, or a big smoothound for that matter). You will see what I mean when you squat on that sloping sea wall and try to lob - this is no place for beachcasters. The floating weed is where the immature crab and rock gobies etc are - and that is where the bass do their feeding. Squat down halfway up the sea wall and keep still. Take a landing net - I hope you will need it.
I don't know anything about camp sites there. Crab and rag can be bought in the tackle shops in the Southend area, website 'Southend Bait and Tackle' comes to mind.
Please put a post on here after your trip - I'd like to know if the old methods still work !